High idle and it wont go down

Hello everyone. Im new here and to the motorcycle world. Back story is i recieved a 1982 kawaski kz 550ltd as payment awhile ago and to the best of my knowledge it was sitting in a barn for about 10+ years. I got all the carbs cleaned, new boots. Pretty much anything that was broke or missing was fixed and replaced. Also these are the original carbs the tk ones. Now these past couple weeks it starts right up with choke then once warm I turn choke off and about 20-30seconds later it revs up to about 4000rpm and wont come down. Ive looked over the throttle cable and its not bunching or sticking and has the right tension. Ive looked over all rubber parts bootsand hoses and haven't seen and damage or cracks. I sprayed some starting fluid where I thought there was some damage but didnt get a reply from the bike. The idle adjustment that sits on top of the carb on the side of the throttle cable isnt a factor. I can un screw it and engine will still rev up. I really dont know where to start or look for any help will be appreciated. 

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Sounds like a vacuum leak.  Spraying stuff on the boots is not a definitive test.  You might want to have another look at the rubber carb boots.

Nessism wrote:

Sounds like a vacuum leak.  Spraying stuff on the boots is not a definitive test.  You might want to have another look at the rubber carb boots.

+1 - to be fair if the boots are original, regardless of how they look they are likely to not seal !!!

First question, who did the carb rebuild? Second question did they set the idle screw to allow adjustment both up and down prior to bench syncing them.
seen far to many carb racks where they have been bench synced without ensuring the idle screw can be backed out to reduce the idle to an acceptable  rpm.

I don't have boots but I have a box of TK carb parts if you have specific needs. The ebay gaskets are good but the jets etc from China are horrible. FYI.

Thanks everyone for your help after I looked closer under better light. The rubber around the  nipple had a hair line crack on the engine side. Got all the parts installed and sounds great. The only trouble im having now  is trying to get the throttle cable adjusted and routed right. Seems like I dont have any slack. Any tips or tricks?